This disclosure relates generally to a Coriolis flow meter for measuring one or more properties of a fluid including fluid flow, and more particularly to a Coriolis flow meter where the fluid flow sub-system is functionally separate from the mechanical oscillator sub-system, and even more particularly to a Coriolis flow meter for use in a bioprocessing system.
Coriolis flow meters are used to measure mass flow of fluids flowing through a pipeline in different industrial process engineering environments. Coriolis flow meters have one or more flow tubes, each having a set of natural vibration modes which may be of a simple bending, torsional, or twisting type. Each material filled flow tube is driven to oscillate at resonance in one of these natural vibration modes. The natural vibration modes are defined in part by the combined mass of the flow tubes and the material within the flow tubes. In most Coriolis flow meters, the fluid flows into the Coriolis flow meter from a connected pipeline on the inlet side. The fluid is then directed through the flow tube or flow tubes and delivered to a pipeline connected on the outlet side.
Typically, the flow tube is oscillated using electromagnetic excitation. When there is no flow through the Coriolis flow meter, all points along a flow tube oscillate with an identical phase. As the material begins to flow, Coriolis accelerations cause each point along the flow tube to have a different phase with respect to other points along the flow tube. Motion sensors on the flow tube produce sinusoidal signals representative of the motion of the flow tube. The phase difference between the sensor signals is proportional to the mass flow rate of the material flowing through the flow tube or flow tubes.
Most Coriolis flow meters are made of metal such as aluminum, steel, stainless steel and titanium. It is known to use Coriolis flow meters having different flow tube configurations. Among these configurations are single tube, dual tubes, straight tube, curved tube, and flow tubes of irregular configuration. The flow tubes also function as a mechanical oscillator.
In these prior art Coriolis flow meters, the frequency range of the oscillation modes is therefore dominated by the design and material of the flow tube, and therefore, choice of material, geometry and thickness of the flow tube has to be tailored to composition, pressure and temperature range, or other such properties of the fluid under test.